Parametric Study of the Hydrostatic Stability of Floating Buildings

Abstract

Given global sea levels are rising, much coastal urban space, which is already extremely valuable, will be under increased risk of flooding. Large pontoons (i.e. floating platforms) in sheltered water supporting buildings could be a sustainable way to expand cities onto water without incurring significant flood risk. The higher the ratio of usable floor area to pontoon footprint (FAR) that can be supported by a pontoon, the more economically feasible the concept becomes, and the taller the construction, the more FAR possible. The goal of this study is therefore to evaluate the relationship between building height and pontoon size considering heel angle (angle of inclination) and freeboard design requirements (where freeboard is the distance from the waterline to the top of the pontoon). To meet this goal, the study analyses the hydrostatic stability of various buildings heights on pontoons of various sizes. It examines, in relation to code requirements, (1) the heeling angle resulting from lateral wind loads and (2) the residual freeboard and freeboard ratio. The heeling angle is also compared to the limit where the pontoon is no longer stable. Results show that a 32m×32m pontoon can support up to 10 stories with a 20m×20m footprint (which gives a FAR of 3.9), and the maximum FAR for a 32m×32m pontoon is roughly 6, consisting of a 7-story building with a footprint of 30m×30m.